Xanthones are a large group of secondary metabolites found in a wide variety of plants. The substitution pattern on the xanthone backbone varies depending upon the nature of the plant source. Mangostins are active principles isolated from Garcinia mangostana L, also known as mangos teen, of the Guttiferace family, which are responsible for mangosteen's anti-inflammatory and many other biological properties. The fruit hull of G. mangostana has been used as a traditional medicine in Southeast Asia for the treatment of diarrhea, inflammation, and ulcers. Mangos teen has been highly popular for their perceived role in enhancing human health (U.S. Pat. No. 6,730,333 B1). The fruit juice made of mangos teen has become a major botanical dietary supplement, and was ranked as one of the top-selling “botanicals” in the Food, beverage & supplement market in 2005 (Nutritional Business Journal, 2006, pp. 186-200). α-Mangostin (2) is the most prominent among more than a dozen xanthone compounds exist in mangos teen. γ-Mangostin, whose structure was deduced as 2,8-bis[(2E)-3-methyl but-2-only)-1,3,6,7-tetrahydroxyxanthen-9-one (1) based on chemical and spectroscopic analysis (Journal of American Chemical Society, 1958, Vol. 80, pp. 1691-1700), is a minor metabolite.
The mangostin compounds were found to inhibit both 5-lipoxygenase and cycloxygenase-2 enzymes (Nakatani, K., et. al., Biochem. Pharmacol, V63: pp 73-79, 2002). γ-Mangostin directly inhibits IKK activity, which specifically phosphorylates IκB, and thereby prevents its degradation and, as a result, induces a decrease in the expression of COX-2 protein and its mRNA by a suppression of NF-κB-dependent transcription. (Nakatani, K., et. al., Biochem. Pharmacol., V66: pp 667-674, 2002).
Despite the established broad spectrum pharmacological activities and long history of usage of the extracts having γ-mangostin, its occurrence in G. mangostana fruit extract is very low and its availability is very limited due to the lack of cost viable processes.
The US patent application 20060014967 relates to a process for obtaining and purifying pure α-mangostin from the rind of the fruit (mangos teen) of Garcinia mangostana. 
WO06137139A1 provide a method of isolating a mangos teen derivative whereby the mangos teen derivative having various pharmacological effects can be efficiently purified by using a highly safe solvent, and a drug and a health food containing the mangos teen derivative having a high safety.
JP2005298379A2 describe an IκB kinase inhibitor inhibiting IκB kinase (a) causing NF-κB activation causing transcriptional enhancement of genes relating to immunity, inflammatory reaction, cell growth control and apoptosis, comprising at least one selected from extracts, extracted from fruits or pericarps of a mangos teen (Garcinia mangostana L.), α-mangostin and γ-mangostin is provided, and a composition containing the inhibitor is provided.
JP08225783A2 describes an antioxidant containing an extract separated from the pericarp of a mangos teen as an active ingredient. The active ingredient is obtained by pulverizing the dried mangos teen, then carrying out the cold leaching with methanol, subsequently partitioning and extracting the methanol extraction essence with acetic acid and water at 1:1 ratio, then treating a part passed into the ethyl acetate by a silica gel chromatography, eluting the resultant extract with n-hexane-ethyl acetate (at 3:1 ratio) and thereby providing the extract as a fraction containing γ-mangostin of the formula.
WO07002666A2, US20060292255A1 and US20060105069A1 relates to pharmaceutical, therapeutic, nutritional, cosmetic, and dermatological compositions derived from the pericarp (rind) of the Garcinia mangostana L plant and the extraction processes used to produce those compositions. This patent application describes compositions comprising an approximately 0.01% to about 80% mixture of a xanthone-rich mangos teen pericarp (rind) extract in novel combinations for pharmaceutical, cosmetic, therapeutic or dermatological compositions that yield surprising health benefits.
All the process patents described above relates to general enrichment of total spectrum of mangostin compounds exist in the Garcinia mangostana fruit pericarp. The specification of the above patent US20060292255A1 though claims inadvertently the enrichment of γ-mangostin upto 40%, no such selective enrichment of γ-mangostin has been attempted or described. The process described therein, which involves merely a base treatment and partitions, could not have achieved the selective enrichment of γ-mangostin over α-mangostin as the physical and chemical properties of the γ-mangostin and α-mangostin are closely similar.
Enriching the γ-mangostin to phytochemical purity from its 3-5% natural abundance commonly exist in the extract, through a process involving column chromatography, as described in patent JP08225783A2 for identification and bio-activity study purposes is not economical for bulk enrichment or commercial utility.
None of the prior art relates to the selective enrichment of γ-mangostin from the natural mangostin extracts derived from Garcinia mangostana. Hence, there exists a need for extracts that offers the health benefits of Garcinia mangostana and comprise prominently and highly enriched in γ-mangostin.
It is, therefore, an object of the present invention to provide a process for producing extracts highly enriched in γ-mangostin and to produce γ-mangostin up to 99% using a commercially viable process.